Re: [PATCH v6 5/5] can: bxcan: add support for ST bxCAN controller

From: Dario Binacchi
Date: Mon Jan 16 2023 - 13:04:06 EST

Hi Vincent,

On Tue, Jan 10, 2023 at 11:25 AM Vincent MAILHOL
<mailhol.vincent@xxxxxxxxxx> wrote:
>
> Hi Dario,
>
> I reviewed it. Overall looks pretty good. Here are a few comments,
> nothing big. You can add my:

Thank you so much for your code review, I really appreciate it.
Sorry if I answer only now but last week was very busy.

>
> Reviewed-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
>
> in next version.

Ok, thanks

>
> On Tue. 10 Jan 2023 at 03:27, Dario Binacchi
> <dario.binacchi@xxxxxxxxxxxxxxxxxxxx> wrote:
> > Add support for the basic extended CAN controller (bxCAN) found in many
> > low- to middle-end STM32 SoCs. It supports the Basic Extended CAN
> > protocol versions 2.0A and B with a maximum bit rate of 1 Mbit/s.
> >
> > The controller supports two channels (CAN1 as master and CAN2 as slave)
> > and the driver can enable either or both of the channels. They share
> > some of the required logic (e. g. clocks and filters), and that means
> > you cannot use the slave CAN without enabling some hardware resources
> > managed by the master CAN.
> >
> > Each channel has 3 transmit mailboxes, 2 receive FIFOs with 3 stages and
> > 28 scalable filter banks.
> > It also manages 4 dedicated interrupt vectors:
> > - transmit interrupt
> > - FIFO 0 receive interrupt
> > - FIFO 1 receive interrupt
> > - status change error interrupt
> >
> > Driver uses all 3 available mailboxes for transmission and FIFO 0 for
> > reception. Rx filter rules are configured to the minimum. They accept
> > all messages and assign filter 0 to CAN1 and filter 14 to CAN2 in
> > identifier mask mode with 32 bits width. It enables and uses transmit,
> > receive buffers for FIFO 0 and error and status change interrupts.
> >
> > Signed-off-by: Dario Binacchi <dario.binacchi@xxxxxxxxxxxxxxxxxxxx>
> >
> > ---
> >
> > (no changes since v5)
> >
> > Changes in v5:
> > - Put static in front of bxcan_enable_filters() definition.
> >
> > Changes in v4:
> > - Add "dt-bindings: arm: stm32: add compatible for syscon gcan node" patch.
> > - Drop the core driver. Thus bxcan-drv.c has been renamed to bxcan.c and
> > moved to the drivers/net/can folder. The drivers/net/can/bxcan directory
> > has therefore been removed.
> > - Use the regmap_*() functions to access the shared memory registers.
> > - Use spinlock to protect bxcan_rmw().
> > - Use 1 space, instead of tabs, in the macros definition.
> > - Drop clock ref-counting.
> > - Drop unused code.
> > - Drop the _SHIFT macros and use FIELD_GET()/FIELD_PREP() directly.
> > - Add BXCAN_ prefix to lec error codes.
> > - Add the macro BXCAN_RX_MB_NUM.
> > - Enable time triggered mode and use can_rx_offload().
> > - Use readx_poll_timeout() in function with timeouts.
> > - Loop from tail to head in bxcan_tx_isr().
> > - Check bits of tsr register instead of pkts variable in bxcan_tx_isr().
> > - Don't return from bxcan_handle_state_change() if skb/cf are NULL.
> > - Enable/disable the generation of the bus error interrupt depending
> > on can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING.
> > - Don't return from bxcan_handle_bus_err() if skb is NULL.
> > - Drop statistics updating from bxcan_handle_bus_err().
> > - Add an empty line in front of 'return IRQ_HANDLED;'
> > - Rename bxcan_start() to bxcan_chip_start().
> > - Rename bxcan_stop() to bxcan_chip_stop().
> > - Disable all IRQs in bxcan_chip_stop().
> > - Rename bxcan_close() to bxcan_ndo_stop().
> > - Use writel instead of bxcan_rmw() to update the dlc register.
> >
> > Changes in v3:
> > - Remove 'Dario Binacchi <dariobin@xxxxxxxxx>' SOB.
> > - Fix the documentation file path in the MAINTAINERS entry.
> > - Do not increment the "stats->rx_bytes" if the frame is remote.
> > - Remove pr_debug() call from bxcan_rmw().
> >
> > Changes in v2:
> > - Fix sparse errors.
> > - Create a MAINTAINERS entry.
> > - Remove the print of the registers address.
> > - Remove the volatile keyword from bxcan_rmw().
> > - Use tx ring algorithm to manage tx mailboxes.
> > - Use can_{get|put}_echo_skb().
> > - Update DT properties.
> >
> > MAINTAINERS | 7 +
> > drivers/net/can/Kconfig | 12 +
> > drivers/net/can/Makefile | 1 +
> > drivers/net/can/bxcan.c | 1110 ++++++++++++++++++++++++++++++++++++++
> > 4 files changed, 1130 insertions(+)
> > create mode 100644 drivers/net/can/bxcan.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index a36df9ed283d..bd246991a3b0 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -4565,6 +4565,13 @@ S: Maintained
> > F: drivers/scsi/BusLogic.*
> > F: drivers/scsi/FlashPoint.*
> >
> > +BXCAN CAN NETWORK DRIVER
> > +M: Dario Binacchi <dario.binacchi@xxxxxxxxxxxxxxxxxxxx>
> > +L: linux-can@xxxxxxxxxxxxxxx
> > +S: Maintained
> > +F: Documentation/devicetree/bindings/net/can/st,stm32-bxcan.yaml
> > +F: drivers/net/can/bxcan.c
> > +
> > C-MEDIA CMI8788 DRIVER
> > M: Clemens Ladisch <clemens@xxxxxxxxxx>
> > L: alsa-devel@xxxxxxxxxxxxxxxx (moderated for non-subscribers)
> > diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
> > index cd34e8dc9394..3ceccafd701b 100644
> > --- a/drivers/net/can/Kconfig
> > +++ b/drivers/net/can/Kconfig
> > @@ -93,6 +93,18 @@ config CAN_AT91
> > This is a driver for the SoC CAN controller in Atmel's AT91SAM9263
> > and AT91SAM9X5 processors.
> >
> > +config CAN_BXCAN
> > + tristate "STM32 Basic Extended CAN (bxCAN) devices"
> > + depends on OF || ARCH_STM32 || COMPILE_TEST
> > + depends on HAS_IOMEM
> > + select CAN_RX_OFFLOAD
> > + help
> > + Say yes here to build support for the STMicroelectronics STM32 basic
> > + extended CAN Controller (bxCAN).
> > +
> > + This driver can also be built as a module. If so, the module
> > + will be called bxcan.
> > +
> > config CAN_CAN327
> > tristate "Serial / USB serial ELM327 based OBD-II Interfaces (can327)"
> > depends on TTY
> > diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
> > index 52b0f6e10668..ff8f76295d13 100644
> > --- a/drivers/net/can/Makefile
> > +++ b/drivers/net/can/Makefile
> > @@ -14,6 +14,7 @@ obj-y += usb/
> > obj-y += softing/
> >
> > obj-$(CONFIG_CAN_AT91) += at91_can.o
> > +obj-$(CONFIG_CAN_BXCAN) += bxcan.o
> > obj-$(CONFIG_CAN_CAN327) += can327.o
> > obj-$(CONFIG_CAN_CC770) += cc770/
> > obj-$(CONFIG_CAN_C_CAN) += c_can/
> > diff --git a/drivers/net/can/bxcan.c b/drivers/net/can/bxcan.c
> > new file mode 100644
> > index 000000000000..7f8831aef9c9
> > --- /dev/null
> > +++ b/drivers/net/can/bxcan.c
> > @@ -0,0 +1,1110 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +//
> > +// bxcan.c - STM32 Basic Extended CAN controller driver
> > +//
> > +// Copyright (c) 2022 Dario Binacchi <dario.binacchi@xxxxxxxxxxxxxxxxxxxx>
> > +//
> > +
> > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> > +
> > +#include <linux/bitfield.h>
> > +#include <linux/can.h>
> > +#include <linux/can/dev.h>
> > +#include <linux/can/error.h>
> > +#include <linux/can/rx-offload.h>
> > +#include <linux/clk.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/iopoll.h>
> > +#include <linux/kernel.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_device.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/regmap.h>
> > +
> > +#define BXCAN_NAPI_WEIGHT 3
> > +#define BXCAN_TIMEOUT_US 10000
> > +
> > +#define BXCAN_RX_MB_NUM 2
> > +#define BXCAN_TX_MB_NUM 3
> > +
> > +/* Master control register (MCR) bits */
> > +#define BXCAN_MCR_DBF BIT(16)
> > +#define BXCAN_MCR_RESET BIT(15)
> > +#define BXCAN_MCR_TTCM BIT(7)
> > +#define BXCAN_MCR_ABOM BIT(6)
> > +#define BXCAN_MCR_AWUM BIT(5)
> > +#define BXCAN_MCR_NART BIT(4)
> > +#define BXCAN_MCR_RFLM BIT(3)
> > +#define BXCAN_MCR_TXFP BIT(2)
> > +#define BXCAN_MCR_SLEEP BIT(1)
> > +#define BXCAN_MCR_INRQ BIT(0)
> > +
> > +/* Master status register (MSR) bits */
> > +#define BXCAN_MSR_RX BIT(11)
> > +#define BXCAN_MSR_SAMP BIT(10)
> > +#define BXCAN_MSR_RXM BIT(9)
>
> This macro, and a dozen other ones, are unused. I am not against
> keeping them. Take this comment as a simple FYI.

You're right, I think it's right to add only what is necessary to
avoid adding unused and maybe even wrong code.
I'll remove unused macros.

>
> > +#define BXCAN_MSR_TXM BIT(8)
> > +#define BXCAN_MSR_SLAKI BIT(4)
> > +#define BXCAN_MSR_WKUI BIT(3)
> > +#define BXCAN_MSR_ERRI BIT(2)
> > +#define BXCAN_MSR_SLAK BIT(1)
> > +#define BXCAN_MSR_INAK BIT(0)
> > +
> > +/* Transmit status register (TSR) bits */
> > +#define BXCAN_TSR_LOW2 BIT(31)
> > +#define BXCAN_TSR_LOW1 BIT(30)
> > +#define BXCAN_TSR_LOW0 BIT(29)
> > +#define BXCAN_TSR_TME_MASK GENMASK(28, 26)
> > +#define BXCAN_TSR_TME2 BIT(28)
> > +#define BXCAN_TSR_TME1 BIT(27)
> > +#define BXCAN_TSR_TME0 BIT(26)
> > +#define BXCAN_TSR_CODE_MASK GENMASK(25, 24)
> > +#define BXCAN_TSR_ABRQ2 BIT(23)
> > +#define BXCAN_TSR_TERR2 BIT(19)
> > +#define BXCAN_TSR_ALST2 BIT(18)
> > +#define BXCAN_TSR_TXOK2 BIT(17)
> > +#define BXCAN_TSR_RQCP2 BIT(16)
> > +#define BXCAN_TSR_ABRQ1 BIT(15)
> > +#define BXCAN_TSR_TERR1 BIT(11)
> > +#define BXCAN_TSR_ALST1 BIT(10)
> > +#define BXCAN_TSR_TXOK1 BIT(9)
> > +#define BXCAN_TSR_RQCP1 BIT(8)
> > +#define BXCAN_TSR_ABRQ0 BIT(7)
> > +#define BXCAN_TSR_TERR0 BIT(3)
> > +#define BXCAN_TSR_ALST0 BIT(2)
> > +#define BXCAN_TSR_TXOK0 BIT(1)
> > +#define BXCAN_TSR_RQCP0 BIT(0)
> > +
> > +/* Receive FIFO 0 register (RF0R) bits */
> > +#define BXCAN_RF0R_RFOM0 BIT(5)
> > +#define BXCAN_RF0R_FOVR0 BIT(4)
> > +#define BXCAN_RF0R_FULL0 BIT(3)
> > +#define BXCAN_RF0R_FMP0_MASK GENMASK(1, 0)
> > +
> > +/* Interrupt enable register (IER) bits */
> > +#define BXCAN_IER_SLKIE BIT(17)
> > +#define BXCAN_IER_WKUIE BIT(16)
> > +#define BXCAN_IER_ERRIE BIT(15)
> > +#define BXCAN_IER_LECIE BIT(11)
> > +#define BXCAN_IER_BOFIE BIT(10)
> > +#define BXCAN_IER_EPVIE BIT(9)
> > +#define BXCAN_IER_EWGIE BIT(8)
> > +#define BXCAN_IER_FOVIE1 BIT(6)
> > +#define BXCAN_IER_FFIE1 BIT(5)
> > +#define BXCAN_IER_FMPIE1 BIT(4)
> > +#define BXCAN_IER_FOVIE0 BIT(3)
> > +#define BXCAN_IER_FFIE0 BIT(2)
> > +#define BXCAN_IER_FMPIE0 BIT(1)
> > +#define BXCAN_IER_TMEIE BIT(0)
> > +
> > +/* Error status register (ESR) bits */
> > +#define BXCAN_ESR_REC_MASK GENMASK(31, 24)
> > +#define BXCAN_ESR_TEC_MASK GENMASK(23, 16)
> > +#define BXCAN_ESR_LEC_MASK GENMASK(6, 4)
> > +#define BXCAN_ESR_BOFF BIT(2)
> > +#define BXCAN_ESR_EPVF BIT(1)
> > +#define BXCAN_ESR_EWGF BIT(0)
> > +
> > +/* Bit timing register (BTR) bits */
> > +#define BXCAN_BTR_SILM BIT(31)
> > +#define BXCAN_BTR_LBKM BIT(30)
> > +#define BXCAN_BTR_SJW_MASK GENMASK(25, 24)
> > +#define BXCAN_BTR_TS2_MASK GENMASK(22, 20)
> > +#define BXCAN_BTR_TS1_MASK GENMASK(19, 16)
> > +#define BXCAN_BTR_BRP_MASK GENMASK(9, 0)
> > +
> > +/* TX mailbox identifier register (TIxR, x = 0..2) bits */
> > +#define BXCAN_TIxR_STID_MASK GENMASK(31, 21)
> > +#define BXCAN_TIxR_EXID_MASK GENMASK(31, 3)
> > +#define BXCAN_TIxR_IDE BIT(2)
> > +#define BXCAN_TIxR_RTR BIT(1)
> > +#define BXCAN_TIxR_TXRQ BIT(0)
> > +
> > +/* TX mailbox data length and time stamp register (TDTxR, x = 0..2 bits */
> > +#define BXCAN_TDTxR_TIME_MASK GENMASK(31, 16)
> > +#define BXCAN_TDTxR_TGT BIT(8)
> > +#define BXCAN_TDTxR_DLC_MASK GENMASK(3, 0)
> > +
> > +/* RX FIFO mailbox identifier register (RIxR, x = 0..1 */
> > +#define BXCAN_RIxR_STID_MASK GENMASK(31, 21)
> > +#define BXCAN_RIxR_EXID_MASK GENMASK(31, 3)
> > +#define BXCAN_RIxR_IDE BIT(2)
> > +#define BXCAN_RIxR_RTR BIT(1)
> > +
> > +/* RX FIFO mailbox data length and timestamp register (RDTxR, x = 0..1) bits */
> > +#define BXCAN_RDTxR_TIME_MASK GENMASK(31, 16)
> > +#define BXCAN_RDTxR_FMI_MASK GENMASK(15, 8)
> > +#define BXCAN_RDTxR_DLC_MASK GENMASK(3, 0)
> > +
> > +#define BXCAN_FMR_REG 0x00
> > +#define BXCAN_FM1R_REG 0x04
> > +#define BXCAN_FS1R_REG 0x0c
> > +#define BXCAN_FFA1R_REG 0x14
> > +#define BXCAN_FA1R_REG 0x1c
> > +#define BXCAN_FiR1_REG(b) (0x40 + (b) * 8)
> > +#define BXCAN_FiR2_REG(b) (0x44 + (b) * 8)
> > +
> > +#define BXCAN_FILTER_ID(master) (master ? 0 : 14)
> > +
> > +/* Filter master register (FMR) bits */
> > +#define BXCAN_FMR_CANSB_MASK GENMASK(13, 8)
> > +#define BXCAN_FMR_FINIT BIT(0)
> > +
> > +enum bxcan_lec_code {
> > + BXCAN_LEC_NO_ERROR = 0,
> > + BXCAN_LEC_STUFF_ERROR,
> > + BXCAN_LEC_FORM_ERROR,
> > + BXCAN_LEC_ACK_ERROR,
> > + BXCAN_LEC_BIT1_ERROR,
> > + BXCAN_LEC_BIT0_ERROR,
> > + BXCAN_LEC_CRC_ERROR,
> > + BXCAN_LEC_UNUSED
> > +};
> > +
> > +/* Structure of the message buffer */
> > +struct bxcan_mb {
> > + u32 id; /* can identifier */
> > + u32 dlc; /* data length control and timestamp */
> > + u32 data[2]; /* data */
> > +};
> > +
> > +/* Structure of the hardware registers */
> > +struct bxcan_regs {
> > + u32 mcr; /* 0x00 - master control */
> > + u32 msr; /* 0x04 - master status */
> > + u32 tsr; /* 0x08 - transmit status */
> > + u32 rf0r; /* 0x0c - FIFO 0 */
> > + u32 rf1r; /* 0x10 - FIFO 1 */
> > + u32 ier; /* 0x14 - interrupt enable */
> > + u32 esr; /* 0x18 - error status */
> > + u32 btr; /* 0x1c - bit timing*/
> > + u32 reserved0[88]; /* 0x20 */
> > + struct bxcan_mb tx_mb[BXCAN_TX_MB_NUM]; /* 0x180 - tx mailbox */
> > + struct bxcan_mb rx_mb[BXCAN_RX_MB_NUM]; /* 0x1b0 - rx mailbox */
> > +};
> > +
> > +struct bxcan_priv {
> > + struct can_priv can;
> > + struct can_rx_offload offload;
> > + struct device *dev;
> > + struct net_device *ndev;
> > +
> > + struct bxcan_regs __iomem *regs;
> > + struct regmap *gcan;
> > + int tx_irq;
> > + int sce_irq;
> > + bool master;
> > + struct clk *clk;
> > + spinlock_t rmw_lock; /* lock for read-modify-write operations */
> > + unsigned int tx_head;
> > + unsigned int tx_tail;
> > + u32 timestamp;
> > +};
> > +
> > +static const struct can_bittiming_const bxcan_bittiming_const = {
> > + .name = KBUILD_MODNAME,
> > + .tseg1_min = 1,
> > + .tseg1_max = 16,
> > + .tseg2_min = 1,
> > + .tseg2_max = 8,
> > + .sjw_max = 4,
> > + .brp_min = 1,
> > + .brp_max = 1024,
> > + .brp_inc = 1,
> > +};
> > +
> > +static inline void bxcan_rmw(struct bxcan_priv *priv, void __iomem *addr,
> > + u32 clear, u32 set)
> > +{
> > + unsigned long flags;
> > + u32 old, val;
> > +
> > + spin_lock_irqsave(&priv->rmw_lock, flags);
> > + old = readl(addr);
> > + val = (old & ~clear) | set;
> > + if (val != old)
> > + writel(val, addr);
> > +
> > + spin_unlock_irqrestore(&priv->rmw_lock, flags);
> > +}
> > +
> > +static void bxcan_disable_filters(struct bxcan_priv *priv, bool master)
> > +{
> > + unsigned int fid = BXCAN_FILTER_ID(master);
> > + u32 fmask = BIT(fid);
> > +
> > + regmap_update_bits(priv->gcan, BXCAN_FA1R_REG, fmask, 0);
> > +}
> > +
> > +static void bxcan_enable_filters(struct bxcan_priv *priv, bool master)
> > +{
> > + unsigned int fid = BXCAN_FILTER_ID(master);
> > + u32 fmask = BIT(fid);
> > +
> > + /* Filter settings:
> > + *
> > + * Accept all messages.
> > + * Assign filter 0 to CAN1 and filter 14 to CAN2 in identifier
> > + * mask mode with 32 bits width.
> > + */
> > +
> > + /* Enter filter initialization mode and assing filters to CAN
> > + * controllers.
> > + */
> > + regmap_update_bits(priv->gcan, BXCAN_FMR_REG,
> > + BXCAN_FMR_CANSB_MASK | BXCAN_FMR_FINIT,
> > + FIELD_PREP(BXCAN_FMR_CANSB_MASK, 14) |
> > + BXCAN_FMR_FINIT);
> > +
> > + /* Deactivate filter */
> > + regmap_update_bits(priv->gcan, BXCAN_FA1R_REG, fmask, 0);
> > +
> > + /* Two 32-bit registers in identifier mask mode */
> > + regmap_update_bits(priv->gcan, BXCAN_FM1R_REG, fmask, 0);
> > +
> > + /* Single 32-bit scale configuration */
> > + regmap_update_bits(priv->gcan, BXCAN_FS1R_REG, fmask, fmask);
> > +
> > + /* Assign filter to FIFO 0 */
> > + regmap_update_bits(priv->gcan, BXCAN_FFA1R_REG, fmask, 0);
> > +
> > + /* Accept all messages */
> > + regmap_write(priv->gcan, BXCAN_FiR1_REG(fid), 0);
> > + regmap_write(priv->gcan, BXCAN_FiR2_REG(fid), 0);
> > +
> > + /* Activate filter */
> > + regmap_update_bits(priv->gcan, BXCAN_FA1R_REG, fmask, fmask);
> > +
> > + /* Exit filter initialization mode */
> > + regmap_update_bits(priv->gcan, BXCAN_FMR_REG, BXCAN_FMR_FINIT, 0);
> > +}
> > +
> > +static inline u8 bxcan_get_tx_head(const struct bxcan_priv *priv)
> > +{
> > + return priv->tx_head % BXCAN_TX_MB_NUM;
> > +}
> > +
> > +static inline u8 bxcan_get_tx_tail(const struct bxcan_priv *priv)
> > +{
> > + return priv->tx_tail % BXCAN_TX_MB_NUM;
> > +}
> > +
> > +static inline u8 bxcan_get_tx_free(const struct bxcan_priv *priv)
> > +{
> > + return BXCAN_TX_MB_NUM - (priv->tx_head - priv->tx_tail);
> > +}
> > +
> > +static bool bxcan_tx_busy(const struct bxcan_priv *priv)
> > +{
> > + if (bxcan_get_tx_free(priv) > 0)
> > + return false;
> > +
> > + netif_stop_queue(priv->ndev);
> > +
> > + /* Memory barrier before checking tx_free (head and tail) */
> > + smp_mb();
> > +
> > + if (bxcan_get_tx_free(priv) == 0) {
> > + netdev_dbg(priv->ndev,
> > + "Stopping tx-queue (tx_head=0x%08x, tx_tail=0x%08x, len=%d).\n",
> > + priv->tx_head, priv->tx_tail,
> > + priv->tx_head - priv->tx_tail);
> > +
> > + return true;
> > + }
> > +
> > + netif_start_queue(priv->ndev);
> > +
> > + return false;
> > +}
> > +
> > +static int bxcan_chip_softreset(struct bxcan_priv *priv)
> > +{
> > + struct bxcan_regs __iomem *regs = priv->regs;
> > + u32 value;
> > +
> > + bxcan_rmw(priv, &regs->mcr, 0, BXCAN_MCR_RESET);
> > + return readx_poll_timeout(readl, &regs->msr, value,
> > + value & BXCAN_MSR_SLAK, BXCAN_TIMEOUT_US,
> > + USEC_PER_SEC);
> > +}
> > +
> > +static int bxcan_enter_init_mode(struct bxcan_priv *priv)
> > +{
> > + struct bxcan_regs __iomem *regs = priv->regs;
> > + u32 value;
> > +
> > + bxcan_rmw(priv, &regs->mcr, 0, BXCAN_MCR_INRQ);
> > + return readx_poll_timeout(readl, &regs->msr, value,
> > + value & BXCAN_MSR_INAK, BXCAN_TIMEOUT_US,
> > + USEC_PER_SEC);
> > +}
> > +
> > +static int bxcan_leave_init_mode(struct bxcan_priv *priv)
> > +{
> > + struct bxcan_regs __iomem *regs = priv->regs;
> > + u32 value;
> > +
> > + bxcan_rmw(priv, &regs->mcr, BXCAN_MCR_INRQ, 0);
> > + return readx_poll_timeout(readl, &regs->msr, value,
> > + !(value & BXCAN_MSR_INAK), BXCAN_TIMEOUT_US,
> > + USEC_PER_SEC);
> > +}
> > +
> > +static int bxcan_enter_sleep_mode(struct bxcan_priv *priv)
> > +{
> > + struct bxcan_regs __iomem *regs = priv->regs;
> > + u32 value;
> > +
> > + bxcan_rmw(priv, &regs->mcr, 0, BXCAN_MCR_SLEEP);
> > + return readx_poll_timeout(readl, &regs->msr, value,
> > + value & BXCAN_MSR_SLAK, BXCAN_TIMEOUT_US,
> > + USEC_PER_SEC);
> > +}
> > +
> > +static int bxcan_leave_sleep_mode(struct bxcan_priv *priv)
> > +{
> > + struct bxcan_regs __iomem *regs = priv->regs;
> > + u32 value;
> > +
> > + bxcan_rmw(priv, &regs->mcr, BXCAN_MCR_SLEEP, 0);
> > + return readx_poll_timeout(readl, &regs->msr, value,
> > + !(value & BXCAN_MSR_SLAK), BXCAN_TIMEOUT_US,
> > + USEC_PER_SEC);
> > +}
> > +
> > +static inline
> > +struct bxcan_priv *rx_offload_to_priv(struct can_rx_offload *offload)
> > +{
> > + return container_of(offload, struct bxcan_priv, offload);
> > +}
> > +
> > +static struct sk_buff *bxcan_mailbox_read(struct can_rx_offload *offload,
> > + unsigned int mbxno, u32 *timestamp,
> > + bool drop)
> > +{
> > + struct bxcan_priv *priv = rx_offload_to_priv(offload);
> > + struct bxcan_regs __iomem *regs = priv->regs;
> > + struct bxcan_mb __iomem *mb_regs = &regs->rx_mb[0];
> > + struct sk_buff *skb = NULL;
> > + struct can_frame *cf;
> > + u32 rf0r, id, dlc;
> > +
> > + rf0r = readl(&regs->rf0r);
> > + if (unlikely(drop)) {
> > + skb = ERR_PTR(-ENOBUFS);
> > + goto mark_as_read;
> > + }
> > +
> > + if (!(rf0r & BXCAN_RF0R_FMP0_MASK))
> > + goto mark_as_read;
> > +
> > + skb = alloc_can_skb(offload->dev, &cf);
> > + if (unlikely(!skb)) {
> > + skb = ERR_PTR(-ENOMEM);
> > + goto mark_as_read;
> > + }
> > +
> > + id = readl(&mb_regs->id);
> > + if (id & BXCAN_RIxR_IDE)
> > + cf->can_id = FIELD_GET(BXCAN_RIxR_EXID_MASK, id) | CAN_EFF_FLAG;
> > + else
> > + cf->can_id = FIELD_GET(BXCAN_RIxR_STID_MASK, id) & CAN_SFF_MASK;
> > +
> > + dlc = readl(&mb_regs->dlc);
> > + priv->timestamp = FIELD_GET(BXCAN_RDTxR_TIME_MASK, dlc);
> > + cf->len = can_cc_dlc2len(FIELD_GET(BXCAN_RDTxR_DLC_MASK, dlc));
> > +
> > + if (id & BXCAN_RIxR_RTR) {
> > + cf->can_id |= CAN_RTR_FLAG;
> > + } else {
> > + int i, j;
> > +
> > + for (i = 0, j = 0; i < cf->len; i += 4, j++)
> > + *(u32 *)(cf->data + i) = readl(&mb_regs->data[j]);
> > + }
> > +
> > + mark_as_read:
> > + rf0r |= BXCAN_RF0R_RFOM0;
> > + writel(rf0r, &regs->rf0r);
> > + return skb;
> > +}
> > +
> > +static irqreturn_t bxcan_rx_isr(int irq, void *dev_id)
> > +{
> > + struct net_device *ndev = dev_id;
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > +
> > + can_rx_offload_irq_offload_fifo(&priv->offload);
> > + can_rx_offload_irq_finish(&priv->offload);
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static irqreturn_t bxcan_tx_isr(int irq, void *dev_id)
> > +{
> > + struct net_device *ndev = dev_id;
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > + struct bxcan_regs __iomem *regs = priv->regs;
> > + struct net_device_stats *stats = &ndev->stats;
> > + u32 tsr, rqcp_bit;
> > + int idx;
> > +
> > + tsr = readl(&regs->tsr);
> > + if (!(tsr & (BXCAN_TSR_RQCP0 | BXCAN_TSR_RQCP1 | BXCAN_TSR_RQCP2)))
> > + return IRQ_HANDLED;
> > +
> > + while (priv->tx_head - priv->tx_tail > 0) {
> > + idx = bxcan_get_tx_tail(priv);
> > + rqcp_bit = BXCAN_TSR_RQCP0 << (idx << 3);
> > + if (!(tsr & rqcp_bit))
> > + break;
> > +
> > + stats->tx_packets++;
> > + stats->tx_bytes += can_get_echo_skb(ndev, idx, NULL);
> > + priv->tx_tail++;
> > + }
> > +
> > + writel(tsr, &regs->tsr);
> > +
> > + if (bxcan_get_tx_free(priv)) {
> > + /* Make sure that anybody stopping the queue after
> > + * this sees the new tx_ring->tail.
> > + */
> > + smp_mb();
> > + netif_wake_queue(ndev);
> > + }
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static void bxcan_handle_state_change(struct net_device *ndev, u32 esr)
> > +{
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > + enum can_state new_state = priv->can.state;
> > + struct can_berr_counter bec;
> > + enum can_state rx_state, tx_state;
> > + struct sk_buff *skb;
> > + struct can_frame *cf;
> > +
> > + /* Early exit if no error flag is set */
> > + if (!(esr & (BXCAN_ESR_EWGF | BXCAN_ESR_EPVF | BXCAN_ESR_BOFF)))
> > + return;
> > +
> > + bec.txerr = FIELD_GET(BXCAN_ESR_TEC_MASK, esr);
> > + bec.rxerr = FIELD_GET(BXCAN_ESR_REC_MASK, esr);
> > +
> > + if (esr & BXCAN_ESR_BOFF)
> > + new_state = CAN_STATE_BUS_OFF;
> > + else if (esr & BXCAN_ESR_EPVF)
> > + new_state = CAN_STATE_ERROR_PASSIVE;
> > + else if (esr & BXCAN_ESR_EWGF)
> > + new_state = CAN_STATE_ERROR_WARNING;
> > +
> > + /* state hasn't changed */
> > + if (unlikely(new_state == priv->can.state))
> > + return;
> > +
> > + skb = alloc_can_err_skb(ndev, &cf);
> > +
> > + tx_state = bec.txerr >= bec.rxerr ? new_state : 0;
> > + rx_state = bec.txerr <= bec.rxerr ? new_state : 0;
> > + can_change_state(ndev, cf, tx_state, rx_state);
> > +
> > + if (new_state == CAN_STATE_BUS_OFF) {
> > + can_bus_off(ndev);
> > + } else if (skb) {
> > + cf->data[6] = bec.txerr;
> > + cf->data[7] = bec.rxerr;
>
> Please set the CAN_ERR_CNT flag in cf->can_id to inform that the error
> counter is available.

Ok.

>
> > + }
> > +
> > + if (skb) {
> > + int err;
> > +
> > + err = can_rx_offload_queue_timestamp(&priv->offload, skb,
> > + priv->timestamp);
> > + if (err)
> > + ndev->stats.rx_fifo_errors++;
> > + }
> > +}
> > +
> > +static void bxcan_handle_bus_err(struct net_device *ndev, u32 esr)
> > +{
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > + enum bxcan_lec_code lec_code;
> > + struct can_frame *cf;
> > + struct sk_buff *skb;
> > +
> > + lec_code = FIELD_GET(BXCAN_ESR_LEC_MASK, esr);
> > +
> > + /* Early exit if no lec update or no error.
> > + * No lec update means that no CAN bus event has been detected
> > + * since CPU wrote BXCAN_LEC_UNUSED value to status reg.
> > + */
> > + if (lec_code == BXCAN_LEC_UNUSED || lec_code == BXCAN_LEC_NO_ERROR)
> > + return;
> > +
> > + /* Common for all type of bus errors */
> > + priv->can.can_stats.bus_error++;
> > +
> > + /* Propagate the error condition to the CAN stack */
> > + skb = alloc_can_err_skb(ndev, &cf);
> > + if (skb)
> > + cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
> > +
> > + switch (lec_code) {
> > + case BXCAN_LEC_STUFF_ERROR:
> > + netdev_dbg(ndev, "Stuff error\n");
> > + ndev->stats.rx_errors++;
> > + if (skb)
> > + cf->data[2] |= CAN_ERR_PROT_STUFF;
> > +
> > + break;
>
> Nitpick: can the "break" be before the newline? It doesn't belong to
> the next switch case code block.

Ok.

>
> > + case BXCAN_LEC_FORM_ERROR:
> > + netdev_dbg(ndev, "Form error\n");
> > + ndev->stats.rx_errors++;
> > + if (skb)
> > + cf->data[2] |= CAN_ERR_PROT_FORM;
> > +
> > + break;
> > + case BXCAN_LEC_ACK_ERROR:
> > + netdev_dbg(ndev, "Ack error\n");
> > + ndev->stats.tx_errors++;
> > + if (skb) {
> > + cf->can_id |= CAN_ERR_ACK;
> > + cf->data[3] = CAN_ERR_PROT_LOC_ACK;
> > + }
> > +
> > + break;
> > + case BXCAN_LEC_BIT1_ERROR:
> > + netdev_dbg(ndev, "Bit error (recessive)\n");
> > + ndev->stats.tx_errors++;
> > + if (skb)
> > + cf->data[2] |= CAN_ERR_PROT_BIT1;
> > +
> > + break;
> > + case BXCAN_LEC_BIT0_ERROR:
> > + netdev_dbg(ndev, "Bit error (dominant)\n");
> > + ndev->stats.tx_errors++;
> > + if (skb)
> > + cf->data[2] |= CAN_ERR_PROT_BIT0;
> > +
> > + break;
> > + case BXCAN_LEC_CRC_ERROR:
> > + netdev_dbg(ndev, "CRC error\n");
> > + ndev->stats.rx_errors++;
> > + if (skb) {
> > + cf->data[2] |= CAN_ERR_PROT_BIT;
> > + cf->data[3] = CAN_ERR_PROT_LOC_CRC_SEQ;
> > + }
> > +
> > + break;
> > + default:
> > + break;
> > + }
> > +
> > + if (skb) {
> > + int err;
> > +
> > + err = can_rx_offload_queue_timestamp(&priv->offload, skb,
> > + priv->timestamp);
> > + if (err)
> > + ndev->stats.rx_fifo_errors++;
> > + }
> > +}
> > +
> > +static irqreturn_t bxcan_state_change_isr(int irq, void *dev_id)
> > +{
> > + struct net_device *ndev = dev_id;
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > + struct bxcan_regs __iomem *regs = priv->regs;
> > + u32 msr, esr;
> > +
> > + msr = readl(&regs->msr);
> > + if (!(msr & BXCAN_MSR_ERRI))
> > + return IRQ_NONE;
> > +
> > + esr = readl(&regs->esr);
> > + bxcan_handle_state_change(ndev, esr);
> > +
> > + if (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
> > + bxcan_handle_bus_err(ndev, esr);
> > +
> > + msr |= BXCAN_MSR_ERRI;
> > + writel(msr, &regs->msr);
> > + can_rx_offload_irq_finish(&priv->offload);
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static int bxcan_chip_start(struct net_device *ndev)
> > +{
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > + struct bxcan_regs __iomem *regs = priv->regs;
> > + struct can_bittiming *bt = &priv->can.bittiming;
> > + u32 clr, set;
> > + int err;
> > +
> > + err = bxcan_chip_softreset(priv);
> > + if (err) {
> > + netdev_err(ndev, "failed to reset chip, error %d\n", err);
>
> Can you print the mnemotechnic instead of the error value?
>
> netdev_err(ndev, "failed to reset chip, error %pe\n",
> ERR_PTR(err));
>
> This comment applies to the other netdev_err() as well.

OK.

>
> > + return err;
> > + }
> > +
> > + err = bxcan_leave_sleep_mode(priv);
> > + if (err) {
> > + netdev_err(ndev, "failed to leave sleep mode, error %d\n", err);
> > + goto failed_leave_sleep;
> > + }
> > +
> > + err = bxcan_enter_init_mode(priv);
> > + if (err) {
> > + netdev_err(ndev, "failed to enter init mode, error %d\n", err);
> > + goto failed_enter_init;
> > + }
> > +
> > + /* MCR
> > + *
> > + * select request order priority
> > + * enable time triggered mode
> > + * bus-off state left on sw request
> > + * sleep mode left on sw request
> > + * retransmit automatically on error
> > + * do not lock RX FIFO on overrun
>
> You are really far from the 80 characters limit. Can you pack this a bit more?

My intention is to list the configurations of the MCR register. As
also done by the flexcan
driver https://elixir.bootlin.com/linux/v5.5.9/source/drivers/net/can/flexcan.c#L1086.

>
> > + */
> > + bxcan_rmw(priv, &regs->mcr,
> > + BXCAN_MCR_ABOM | BXCAN_MCR_AWUM | BXCAN_MCR_NART |
> > + BXCAN_MCR_RFLM, BXCAN_MCR_TTCM | BXCAN_MCR_TXFP);
> > +
> > + /* Bit timing register settings */
> > + set = FIELD_PREP(BXCAN_BTR_BRP_MASK, bt->brp - 1) |
> > + FIELD_PREP(BXCAN_BTR_TS1_MASK, bt->phase_seg1 +
> > + bt->prop_seg - 1) |
> > + FIELD_PREP(BXCAN_BTR_TS2_MASK, bt->phase_seg2 - 1) |
> > + FIELD_PREP(BXCAN_BTR_SJW_MASK, bt->sjw - 1);
> > +
> > + /* loopback + silent mode put the controller in test mode,
> > + * useful for hot self-test
> > + */
> > + if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
> > + set |= BXCAN_BTR_LBKM;
> > +
> > + if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
> > + set |= BXCAN_BTR_SILM;
> > +
> > + netdev_dbg(ndev,
> > + "TQ[ns]: %d, PrS: %d, PhS1: %d, PhS2: %d, SJW: %d, BRP: %d, CAN_BTR: 0x%08x\n",
> > + bt->tq, bt->prop_seg, bt->phase_seg1, bt->phase_seg2,
> > + bt->sjw, bt->brp, set);
>
> Is this debug really needed? You can use "ip link" to display these.

I will remove it.

>
> > + bxcan_rmw(priv, &regs->btr, BXCAN_BTR_SILM | BXCAN_BTR_LBKM |
> > + BXCAN_BTR_BRP_MASK | BXCAN_BTR_TS1_MASK | BXCAN_BTR_TS2_MASK |
> > + BXCAN_BTR_SJW_MASK, set);
> > +
> > + bxcan_enable_filters(priv, priv->master);
> > +
> > + /* Clear all internal status */
> > + priv->tx_head = 0;
> > + priv->tx_tail = 0;
> > +
> > + err = bxcan_leave_init_mode(priv);
> > + if (err) {
> > + netdev_err(ndev, "failed to leave init mode, error %d\n", err);
> > + goto failed_leave_init;
> > + }
> > +
> > + /* Set a `lec` value so that we can check for updates later */
> > + bxcan_rmw(priv, &regs->esr, BXCAN_ESR_LEC_MASK,
> > + FIELD_PREP(BXCAN_ESR_LEC_MASK, BXCAN_LEC_UNUSED));
> > +
> > + /* IER
> > + *
> > + * Enable interrupt for:
> > + * bus-off
> > + * passive error
> > + * warning error
> > + * last error code
> > + * RX FIFO pending message
> > + * TX mailbox empty
> > + */
> > + clr = BXCAN_IER_WKUIE | BXCAN_IER_SLKIE | BXCAN_IER_FOVIE1 |
> > + BXCAN_IER_FFIE1 | BXCAN_IER_FMPIE1 | BXCAN_IER_FOVIE0 |
> > + BXCAN_IER_FFIE0;
> > + set = BXCAN_IER_ERRIE | BXCAN_IER_BOFIE | BXCAN_IER_EPVIE |
> > + BXCAN_IER_EWGIE | BXCAN_IER_FMPIE0 | BXCAN_IER_TMEIE;
> > +
> > + if (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
> > + set |= BXCAN_IER_LECIE;
> > + else
> > + clr |= BXCAN_IER_LECIE;
> > +
> > + bxcan_rmw(priv, &regs->ier, clr, set);
> > +
> > + priv->can.state = CAN_STATE_ERROR_ACTIVE;
> > + return 0;
> > +
> > +failed_leave_init:
> > +failed_enter_init:
> > +failed_leave_sleep:
> > + bxcan_chip_softreset(priv);
> > + return err;
> > +}
> > +
> > +static int bxcan_open(struct net_device *ndev)
> > +{
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > + int err;
> > +
> > + err = open_candev(ndev);
> > + if (err) {
> > + netdev_err(ndev, "open_candev() failed, error %d\n", err);
> > + return err;
> > + }
> > +
> > + can_rx_offload_enable(&priv->offload);
> > + err = request_irq(ndev->irq, bxcan_rx_isr, IRQF_SHARED, ndev->name,
> > + ndev);
> > + if (err) {
> > + netdev_err(ndev, "failed to register rx irq(%d), error %d\n",
> > + ndev->irq, err);
> > + goto out_close_candev;
> > + }
> > +
> > + err = request_irq(priv->tx_irq, bxcan_tx_isr, IRQF_SHARED, ndev->name,
> > + ndev);
> > + if (err) {
> > + netdev_err(ndev, "failed to register tx irq(%d), error %d\n",
> > + priv->tx_irq, err);
> > + goto out_free_rx_irq;
> > + }
> > +
> > + err = request_irq(priv->sce_irq, bxcan_state_change_isr, IRQF_SHARED,
> > + ndev->name, ndev);
> > + if (err) {
> > + netdev_err(ndev, "failed to register sce irq(%d), error %d\n",
> > + priv->sce_irq, err);
> > + goto out_free_tx_irq;
> > + }
> > +
> > + err = bxcan_chip_start(ndev);
> > + if (err)
> > + goto out_free_sce_irq;
> > +
> > + netif_start_queue(ndev);
> > + return 0;
> > +
> > +out_free_sce_irq:
> > + free_irq(priv->sce_irq, ndev);
> > +out_free_tx_irq:
> > + free_irq(priv->tx_irq, ndev);
> > +out_free_rx_irq:
> > + free_irq(ndev->irq, ndev);
> > +out_close_candev:
> > + can_rx_offload_disable(&priv->offload);
> > + close_candev(ndev);
> > + return err;
> > +}
> > +
> > +static void bxcan_chip_stop(struct net_device *ndev)
> > +{
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > + struct bxcan_regs __iomem *regs = priv->regs;
> > +
> > + /* disable all interrupts */
> > + bxcan_rmw(priv, &regs->ier, BXCAN_IER_SLKIE | BXCAN_IER_WKUIE |
> > + BXCAN_IER_ERRIE | BXCAN_IER_LECIE | BXCAN_IER_BOFIE |
> > + BXCAN_IER_EPVIE | BXCAN_IER_EWGIE | BXCAN_IER_FOVIE1 |
> > + BXCAN_IER_FFIE1 | BXCAN_IER_FMPIE1 | BXCAN_IER_FOVIE0 |
> > + BXCAN_IER_FFIE0 | BXCAN_IER_FMPIE0 | BXCAN_IER_TMEIE, 0);
> > + bxcan_disable_filters(priv, priv->master);
> > + bxcan_enter_sleep_mode(priv);
> > + priv->can.state = CAN_STATE_STOPPED;
> > +}
> > +
> > +static int bxcan_stop(struct net_device *ndev)
> > +{
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > +
> > + netif_stop_queue(ndev);
> > + bxcan_chip_stop(ndev);
> > + free_irq(ndev->irq, ndev);
> > + free_irq(priv->tx_irq, ndev);
> > + free_irq(priv->sce_irq, ndev);
> > + can_rx_offload_disable(&priv->offload);
> > + close_candev(ndev);
> > + return 0;
> > +}
> > +
> > +static netdev_tx_t bxcan_start_xmit(struct sk_buff *skb,
> > + struct net_device *ndev)
> > +{
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > + struct can_frame *cf = (struct can_frame *)skb->data;
> > + struct bxcan_regs __iomem *regs = priv->regs;
> > + struct bxcan_mb __iomem *mb_regs;
> > + unsigned int idx;
> > + u32 id;
> > + int i, j;
> > +
> > + if (can_dropped_invalid_skb(ndev, skb))
> > + return NETDEV_TX_OK;
> > +
> > + if (bxcan_tx_busy(priv))
> > + return NETDEV_TX_BUSY;
>
> Normally, you are not supposed to return NETDEV_TX_BUSY. Can you
> confirm that this is just a safety net and that this is not supposed
> to happen? (Code looks OK, I am really just asking to double check).

The mailbox is not very deep, so under load there may be no space left for
the message to be transmitted. This is a protection scheme that I had already
used in my previous commit on the c_can driver:
28e86e9ab522e65b08545e5008d0f1ac5b19dad1 (" can: c_can: support tx
ring algorithm").

>
> > + idx = bxcan_get_tx_head(priv);
> > + priv->tx_head++;
> > + if (bxcan_get_tx_free(priv) == 0)
> > + netif_stop_queue(ndev);
> > +
> > + mb_regs = &regs->tx_mb[idx];
> > + if (cf->can_id & CAN_EFF_FLAG)
> > + id = FIELD_PREP(BXCAN_TIxR_EXID_MASK, cf->can_id) |
> > + BXCAN_TIxR_IDE;
> > + else
> > + id = FIELD_PREP(BXCAN_TIxR_STID_MASK, cf->can_id);
> > +
> > + if (cf->can_id & CAN_RTR_FLAG)
> > + id |= BXCAN_TIxR_RTR;
> > +
> > + writel(FIELD_PREP(BXCAN_TDTxR_DLC_MASK, cf->len), &mb_regs->dlc);
> > +
> > + for (i = 0, j = 0; i < cf->len; i += 4, j++)
> > + writel(*(u32 *)(cf->data + i), &mb_regs->data[j]);
>
> Do not copy the data if CAN_RTR_FLAG is set.
>
> > + can_put_echo_skb(skb, ndev, idx, 0);
> > +
> > + /* Start transmission */
> > + writel(id | BXCAN_TIxR_TXRQ, &mb_regs->id);
> > +
> > + return NETDEV_TX_OK;
> > +}
> > +
> > +static const struct net_device_ops bxcan_netdev_ops = {
> > + .ndo_open = bxcan_open,
> > + .ndo_stop = bxcan_stop,
> > + .ndo_start_xmit = bxcan_start_xmit,
> > + .ndo_change_mtu = can_change_mtu,
> > +};
> > +
> > +static int bxcan_do_set_mode(struct net_device *ndev, enum can_mode mode)
> > +{
> > + int err;
> > +
> > + switch (mode) {
> > + case CAN_MODE_START:
> > + err = bxcan_chip_start(ndev);
> > + if (err)
> > + return err;
> > +
> > + netif_wake_queue(ndev);
> > + break;
> > + default:
> > + return -EOPNOTSUPP;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int bxcan_get_berr_counter(const struct net_device *ndev,
> > + struct can_berr_counter *bec)
> > +{
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > + struct bxcan_regs __iomem *regs = priv->regs;
> > + u32 esr;
> > + int err;
> > +
> > + err = clk_prepare_enable(priv->clk);
> > + if (err)
> > + return err;
> > +
> > + esr = readl(&regs->esr);
> > + bec->txerr = FIELD_GET(BXCAN_ESR_TEC_MASK, esr);
> > + bec->rxerr = FIELD_GET(BXCAN_ESR_REC_MASK, esr);
> > + clk_disable_unprepare(priv->clk);
> > + return 0;
> > +}
> > +
> > +static int bxcan_probe(struct platform_device *pdev)
> > +{
> > + struct device_node *np = pdev->dev.of_node;
> > + struct device *dev = &pdev->dev;
> > + struct net_device *ndev;
> > + struct bxcan_priv *priv;
> > + struct clk *clk = NULL;
> > + void __iomem *regs;
> > + struct regmap *gcan;
> > + bool master;
> > + int err, rx_irq, tx_irq, sce_irq;
> > +
> > + regs = devm_platform_ioremap_resource(pdev, 0);
> > + if (IS_ERR(regs)) {
> > + dev_err(dev, "failed to get base address\n");
> > + return PTR_ERR(regs);
> > + }
> > +
> > + gcan = syscon_regmap_lookup_by_phandle(np, "st,gcan");
> > + if (IS_ERR(gcan)) {
> > + dev_err(dev, "failed to get shared memory base address\n");
> > + return PTR_ERR(gcan);
> > + }
> > +
> > + master = of_property_read_bool(np, "st,can-master");
> > + clk = devm_clk_get(dev, NULL);
> > + if (IS_ERR(clk)) {
> > + dev_err(dev, "failed to get clock\n");
> > + return PTR_ERR(clk);
> > + }
> > +
> > + rx_irq = platform_get_irq_byname(pdev, "rx0");
> > + if (rx_irq < 0) {
> > + dev_err(dev, "failed to get rx0 irq\n");
> > + return rx_irq;
> > + }
> > +
> > + tx_irq = platform_get_irq_byname(pdev, "tx");
> > + if (tx_irq < 0) {
> > + dev_err(dev, "failed to get tx irq\n");
> > + return tx_irq;
> > + }
> > +
> > + sce_irq = platform_get_irq_byname(pdev, "sce");
> > + if (sce_irq < 0) {
> > + dev_err(dev, "failed to get sce irq\n");
> > + return sce_irq;
> > + }
> > +
> > + ndev = alloc_candev(sizeof(struct bxcan_priv), BXCAN_TX_MB_NUM);
> > + if (!ndev) {
> > + dev_err(dev, "alloc_candev() failed\n");
> > + return -ENOMEM;
> > + }
> > +
> > + priv = netdev_priv(ndev);
> > + platform_set_drvdata(pdev, ndev);
> > + SET_NETDEV_DEV(ndev, dev);
> > + ndev->netdev_ops = &bxcan_netdev_ops;
>
> Can you also populate ndev->ethtool_ops with the default timestamp info? c.f.

Ok.

>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=409c188c57cd
>
> > + ndev->irq = rx_irq;
> > + ndev->flags |= IFF_ECHO;
> > +
> > + priv->dev = dev;
> > + priv->ndev = ndev;
> > + priv->regs = regs;
> > + priv->gcan = gcan;
> > + priv->clk = clk;
> > + priv->tx_irq = tx_irq;
> > + priv->sce_irq = sce_irq;
> > + priv->master = master;> + priv->can.clock.freq = clk_get_rate(clk);
> > + spin_lock_init(&priv->rmw_lock);
> > + priv->tx_head = 0;
> > + priv->tx_tail = 0;
> > + priv->can.bittiming_const = &bxcan_bittiming_const;
> > + priv->can.do_set_mode = bxcan_do_set_mode;
> > + priv->can.do_get_berr_counter = bxcan_get_berr_counter;
> > + priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
> > + CAN_CTRLMODE_LISTENONLY | CAN_CTRLMODE_BERR_REPORTING;
>
> Does this device allow to send and receive frames with DLC greater
> than 8? c.f. CAN_CTRLMODE_CC_LEN8_DLC.

No, 0 to 8. I checked on the reference manual.

Soon I will send version 7 of the series. I've added your
'Reviewed-by' tag as you write at
the top of the email. But please let me know if I did something wrong
in applying or not some
of your suggestions.

Thanks and regards,

Dario

>
> > + priv->offload.mailbox_read = bxcan_mailbox_read;
> > + err = can_rx_offload_add_fifo(ndev, &priv->offload, BXCAN_NAPI_WEIGHT);
> > + if (err) {
> > + dev_err(dev, "failed to add FIFO rx_offload\n");
> > + goto out_free_candev;
> > + }
> > +
> > + err = clk_prepare_enable(priv->clk);
> > + if (err) {
> > + dev_err(dev, "failed to enable clock\n");
> > + goto out_can_rx_offload_del;
> > + }
> > +
> > + err = register_candev(ndev);
> > + if (err) {
> > + dev_err(dev, "failed to register netdev\n");
> > + goto out_clk_disable_unprepare;
> > + }
> > +
> > + dev_info(dev, "clk: %d Hz, IRQs: %d, %d, %d\n", priv->can.clock.freq,
> > + tx_irq, rx_irq, sce_irq);
> > + return 0;
> > +
> > +out_clk_disable_unprepare:
> > + clk_disable_unprepare(priv->clk);
> > +out_can_rx_offload_del:
> > + can_rx_offload_del(&priv->offload);
> > +out_free_candev:
> > + free_candev(ndev);
> > + return err;
> > +}
> > +
> > +static int bxcan_remove(struct platform_device *pdev)
> > +{
> > + struct net_device *ndev = platform_get_drvdata(pdev);
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > +
> > + unregister_candev(ndev);
> > + clk_disable_unprepare(priv->clk);
> > + can_rx_offload_del(&priv->offload);
> > + free_candev(ndev);
> > + return 0;
> > +}
> > +
> > +static int __maybe_unused bxcan_suspend(struct device *dev)
> > +{
> > + struct net_device *ndev = dev_get_drvdata(dev);
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > +
> > + if (!netif_running(ndev))
> > + return 0;
> > +
> > + netif_stop_queue(ndev);
> > + netif_device_detach(ndev);
> > +
> > + bxcan_enter_sleep_mode(priv);
> > + priv->can.state = CAN_STATE_SLEEPING;
> > + clk_disable_unprepare(priv->clk);
> > + return 0;
> > +}
> > +
> > +static int __maybe_unused bxcan_resume(struct device *dev)
> > +{
> > + struct net_device *ndev = dev_get_drvdata(dev);
> > + struct bxcan_priv *priv = netdev_priv(ndev);
> > +
> > + if (!netif_running(ndev))
> > + return 0;
> > +
> > + clk_prepare_enable(priv->clk);
> > + bxcan_leave_sleep_mode(priv);
> > + priv->can.state = CAN_STATE_ERROR_ACTIVE;
> > +
> > + netif_device_attach(ndev);
> > + netif_start_queue(ndev);
> > + return 0;
> > +}
> > +
> > +static SIMPLE_DEV_PM_OPS(bxcan_pm_ops, bxcan_suspend, bxcan_resume);
> > +
> > +static const struct of_device_id bxcan_of_match[] = {
> > + {.compatible = "st,stm32f4-bxcan"},
> > + { /* sentinel */ },
> > +};
> > +MODULE_DEVICE_TABLE(of, bxcan_of_match);
> > +
> > +static struct platform_driver bxcan_driver = {
> > + .driver = {
> > + .name = KBUILD_MODNAME,
> > + .pm = &bxcan_pm_ops,
> > + .of_match_table = bxcan_of_match,
> > + },
> > + .probe = bxcan_probe,
> > + .remove = bxcan_remove,
> > +};
> > +
> > +module_platform_driver(bxcan_driver);
> > +
> > +MODULE_AUTHOR("Dario Binacchi <dario.binacchi@xxxxxxxxxxxxxxxxxxxx>");
> > +MODULE_DESCRIPTION("STMicroelectronics Basic Extended CAN controller driver");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.32.0
> >



--

Dario Binacchi

Senior Embedded Linux Developer

dario.binacchi@xxxxxxxxxxxxxxxxxxxx

__________________________________


Amarula Solutions SRL

Via Le Canevare 30, 31100 Treviso, Veneto, IT

T. +39 042 243 5310
info@xxxxxxxxxxxxxxxxxxxx

www.amarulasolutions.com